1. Field of Invention
The invention concerns a process and device for monitoring the free space in the direction of travel of a vehicle according to the precharacterizing portion of patent claims 1 and 10.
2. Related Art of the Invention
In complex vehicle maneuvers it is often difficult for the driver of the motor vehicle to predict the precise track of the vehicle and to know how much free space will be needed in order to avoid collision. This is the case in particular when the vehicle operator is not familiar with the dimensions or the maneuvering characteristics of the vehicle.
In order to support the vehicle operator during difficult driving maneuvers, an operator information system has been developed as described in Japanese Published Application JP 2000-67395 A, wherein image data describing the roadway have predicted vehicle tracks superimposed thereupon. In this manner it becomes possible for the vehicle operator to better estimate the future behavior of his vehicle. To do this the system uses the data of two sensors, which are mounted on the front wheels of the vehicle and therewith provide information regarding the direction of motion and the speed of the vehicle. From the sensor data a future vehicle track is predicted and this is superimposed as a line structure of a depiction of the vehicle track in a display unit. A disadvantage with such a system is that the predicted vehicle track is superimposed only upon a display of the vehicle roadway or route, with no images embedded in the display providing the operator information regarding objects in the vicinity of the vehicle.
In order to provide the vehicle operator an improved overview over the actual environment of the vehicle and to allow better maneuvering therein, an improved environment monitoring system is proposed in Patent Application EP 1 158 803 A2. Herein the situation of the environment of the vehicle is detected using multiple camera systems, with data transformed into a birdseye view. Into this image a vehicle system representing the vehicle is embedded in a position corresponding to the vehicle position. The vehicle symbol is herein so designed, that it fits into the environment image with its correct size relationship. The image information provided to the vehicle operator thus corresponds to the view from the point above the vehicle looking down onto the environment; that is, the vehicle and its environment are represented in a type of birdseye perspective. In order to support the vehicle operator in his evaluation of the future travel path of the vehicle, the image has superimposed thereon a three dimensional line contour describing the predicted vehicle path of travel. The line contour represents the image of an edge or frame of a rectangle, which is curved along the predicted path of travel. The two lower longitudinal edges of the rectangle lie on the vehicle path of travel and correspond substantially to the vehicle track represnted in JP 2000-67395 A. The height and breadth of the rectangle is herein selected to be smaller than height and breadth of the vehicle. The vehicle operator obtains by this mode of representation on the one hand a good depiction of the future relationship of the vehicle to its environment; however, due to the perspective of representation which is unconventional for the vehicle operator it is not possible for him, in simple manner to grasp the danger of collision, which would be attributable to the parts projecting from the vehicle sides into the area of the predicted vehicle path of travel. In particular, the parts projecting into the predicted vehicle path from above can only be represented and recognized with difficulty. It is also not possible to represent for the vehicle operator thoroughfares (tunnels or entryways, garages) in a plausible or intuitively understandable manner.